The Foel Drygarn quarries -- what is the evidence?

The main western Foel Drygarn quarrying area.  The burial mounds are on the skyline.  The hillfort entrance is near the right edge of the photo.  The crags are the "western rhyolite and tuff crags".  Most of the quarrying traces are beneath the crags at bottom left, connected by a substantial trackway to the burial mounds.  Just to the right of centre we can see the trackway on the upper terrace, where there are also quarrying traces.

The western rhyolite crag at Foel Drygarn.  The main quarrying area was beneath this crag 

at bottom left.

Map of the main features referred to in the text

It occurs to me that by using the term "quarries" in my last post I might be be accused of jumping to desirable conclusions, just as MPP and his gang did when they turned up at Rhosyfelin and Carn Goedog. They were convinced (before they arrived) that there had to be Neolithic quarries at those sites because the geologists had told them that there were precise geological matches between certain Stonehenge fragments and monoliths and the rocks that were outcropping at the ground surface. They were also told (by people who should have known better) that glacial stone transport was impossible -- so matter how unlikely the idea of human monolith transport was, it had to be true. That was the context, and look where it has led them.......

At Foel Drygarn, I had no particular wish to find quarries, but on looking at the features on the ground I began to see things that really allowed no other interpretation. If you look at things and can find no natural explanation for them, then human involvement becomes an option. I have laid out the evidence, in a somewhat disorganised fashion, in this post:

https://brian-mountainman.blogspot.com/2018/10/the-prehistoric-quarries-at-foel-drygarn.html

In the literature (including the main Coflein site description) there are hardly any references to quarrying.  However, in the 1968 map made by RCAHMW quarries ARE referred to without comment -- but only to the east of the hillfort entrance.  https://coflein.gov.uk/en/site/94948/images

Extract from the 1968 map, showing a dozen or so small quarrying pits to the east of the hillfort entrance. Note that nothing is marked on the map beneath the western crags, and there are no comments about the quarrying features.

I have examined the pits in the slope to the east of the hillfort entrance and agree with the RCAHMW mapmakers that they are probably quarrying or extraction pits.  But I don't think they are on a sufficient scale to have provided all of the 4,000 tonnes of rocks needed for the building of the burial mounds.  Some of the material must have come from a little further afield. 

So let's just systematically summarise the evidence that has led me to refer to quarrying and quarries, particularly in association with the western crags:

1. Along the southern edge of the fortified area on the summit of Foel Drygarn there are four prominent crags and several smaller ones. The biggest eastern crag (one of three) (close to the eastern burial mound) is really a tor made of dolerite, similar in many ways to the other tors scattered across the eastern Preseli landscape. It has obvious traces of ice moulding. The other crags, to the west of the western burial mound, are sharper and more "craggy", and are geologically complex -- made of rhyolite, felspathic tuffs and other rock types associated with extrusive volcanic activity.

2. On the steep slopes on the southern flanks of these rock outcrops there are, as you might expect, rockfall accumulations associated with frost-shattering and other periglacial processes that have operated over many thousands of years.

3. But the interesting thing about these accumulations is that they are composed mostly of boulders and big rock slabs weighing more than 100kg. Where have the smaller sharp-edged fragments gone? Could they have been selectively removed?

The easternmost dolerite tor, with a jumble of rockfall debris from which most of the finer 

material has been removed.  The two smaller dolerite tors (see image at the top of this post) have been substantially "cleaned up" through the removal of debris.

4. Within 150m of these rock outcrops are the three famous Foel Drygarn burial mounds, built of in excess of 4,000 tonnes of rock slabs and small boulders. The eastern tor is only 30 m from the eastern mound, and the westernmost crag is about 130m away from the western mound. Access between all of these features is easy, and there are well defined interconnecting trackways that look as if they have existed for a very long time. The hillfort entrance, and the main access route from the south, are clearly defined and visible on satellite imagery.

The surface of one of the burial mounds.  This is typical scree / rockfall material -- all derived from the adjaacent igneous crags.  The rocks are of dolerite, rhyolite and ash -- suggestive of collection from many different locations around the hill summit.

5. Two well defined trackways run approx west-east along the slope at the foot of the western crags, joining the main access track at the hillfort entrance.

On this image, left of centre, we can see the trackway leading to the hillfort entrance.  It also connects the three burial mounds with the quarrying area, and must have been used as the stone transport route prior to the construction of the hillfort.

6. On a high terrace or bench beneath the group of volcanic ash rags closest to the entrance passage, there are undulating pitted surfaces with slight ridges and mounds which cannot easily be explained by reference to natural processes.  These are interpreted as signs of rubble and stone extraction.

7. Beneath the more spectacular crags to the west, there is a lower terrace which must originally have supported thick accumulations of rockfall debris and scree.  Much of this debris has been removed. The extraction pits are clearly visible, separated by ridges of grassed-over rubble c1m high.

8.  In gullies between the crags we can still see accumulations of scree, with sharp-edges slabs and blocks that are virtually identical to the fragments seen on the burial mounds.

Rockfall debris exposed in a gully beneath the western crags

I have not mapped this site carefully, or conducted any excavations; but I am confident that we have all the characteristics of a Bronze Age (and possibly later) stone quarry -- not used for monoliths, but for rubble and easily transported slabs.  We have a destination for this material, an adjacent source, and a transport route.  We have a motivation, and we have many physical traces that cannot, I think, be explained by reference to natural processes.

Quarrying activity here was much more extensive than indicated on the 1968 RCAHMW map.

As I mentioned in an earlier post, no elaborate engineering and no quarrying tools were needed here.  Stones were just picked up from the scree and rubble derived from rockfalls, and carried away, mostly by individuals and maybe sometimes (for stones weighing over 20 kg) by a couples of men working together.

So this is a quarrying site, and I make no apologies for referring to it as such.  If anybody wants to argue with me, let's have an interesting conversation........

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PS.  Now here is an interesting question.  Did the people who built the burial mounds and took the stone from the quarries have access to wheeled vehicles?  They might have done -- apparently wheels first appeared in the Bronze Age in Britain. But if they did, the vehicles were probably very heavy, with solid wooden wheels cut from tree trunks.   They might have been useful on dry flat land -- but for carrying loads of rocks uphill in this challenging terrain?  I have my doubts.